Obesity is one of the most obvious but unappreciated public health challenges that affect individuals of all ages leading to serious health problems such as hypertension and type 2 diabetes. Due to their lack of physical activity, adolescents are more prone to obesity. The goal of this study was to examine the adolescents’ risk perceptions about obesity and its related diseases in selected senior high schools in the Greater Kumasi. A descriptive cross-sectional research design was used in this study. A total of one hundred (100) students from each of the seven (7) schools were included in the study. The sample size was determined using the Cochran single proportion population calculation. Based on the 17.1% prevalence of overweight and obesity among Senior High school students in Greater Kumasi and a significance level of 5%, the sample size was estimated with a confidence range of 95% and a significance level of 5%. A simple random sampling procedure was utilised to ensure that each student from the chosen schools had an equal chance of being chosen. A questionnaire was used as the main instrument for the data collection. Data were analysed using descriptive statistics. The study revealed that respondents had a high-risk perception of obesity particularly when it comes to its ability to affect their health status. It was concluded that obesity has little influence on the majority of respondents' ability to concentrate in class or limit their involvement in physical activities. The school authorities should re-educate students on how obesity can hurt their concentration level as well as their physical competence.